Air conditioner



Nov. 12, 1968 K. E. MARSTELLER AIR CONDIT IONER Filed Feb. 15, 1967INVENTOR. Ki/VA/[Tb I. MlifffZZf/V l I I WMQZM m United States Patent3,410,105 AIR CONDITIONER Kenneth E. Marsteller, Willow Grove, Pa.,assignor to Philco-Ford Corporation, Philadelphia, Pa., a corporation ofDelaware Filed Feb. 15, 1967, Ser. No. 616,310 Claims. (Cl. 62180)ABSTRACT OF THE DISCLOSURE An air conditioner having a temperaturecontrol system which, in addition to cyling the compressor betweenpredetermined temperature limits, modulates air flow passing over theevaporator and into the room in accordance with room temperatures inexcess of such limits. Modulation of air flow is accomplished by varyingthe speed of the fan motor inducing such flow, through a solid stateelectrical circuit controlled by an optical system comprising a lamp, aphotocell, and an interposed shutter arrangement actuated by thethermostat.

This invention relates to air conditioners, and more particularly toimprovements in temperature control systems for room air conditioners.

Temperature control can be achieved, to some degree, by varying the flowrate of room air over an air conditioner evaporator or cooling coil. Ifthe air flow rates are maintained according to room temperatures fallingwithin a very small temperature range, the room temperature can be heldwithin such range as long as the existing cooling load requirements fallwithin the range of cooling capacity defined by the highest and lowestair flow rates. However, practical considerations, such for example asthe tendency for ice to form on the coil at reduced loading, limit theminimum air flow rate to a value of about 50% of the maximum flow rate.An air flow rate of this order has been found to achieve a reduction incooling capacity to a value of about 75% of maxim-um. For cooling loadsrequiring cooling capacity less than 75% of the maximum, means may beprovided for cycling the cooling coil, as well as modulating the airflow rate, to maintain control of room temperature.

It is .a general objective of this invention to provide improved controlapparatus affording a broad range of control, which apparatus is readilyadaptable for use in a room air conditioner of otherwise conventionaldesign.

Summary of the invention The present invention is directed toachievement of such control through a unique and simple modification ofa conventional air conditioner thermostat mechanism of the type in whichtemperature variations are accompanied by motion of a linkage which, atthe end of its travel, actuates the compressor energizing switch. It isproposed, in accordance with the invention, to drive a shutter or othersuitable vane means by this linkage, which shutter is interposed betweena light source and a photocell. Movement of the shutter is such that thelinkage motion prior to switch acuation is translated into changes inphotocell illumination. The resultant variable signal from the photocellis used to operate means for changing evaporator air flow from maximumto minimum. Preferably, the mechanism is so constructed and arrangedthat thesignal for minimum fiow will occur just prior to actuation ofthe compressor switch to deenergize the compressor.

Brief description of the drawing The manner in which the generalobjectives and advantages of the invention may best be achieved will be3,419,105 Patented Nov. 12, 1968 understood from a consideration of thefollowing description, taken in light of the accompanying drawing inwhich:

FIGURE 1 is a perspective view of a room air conditioner embodying theinvention;

FIGURE 2 is a generally horizontal sectional view of apparatus seen inFIGURE 1, with parts broken away;

FIGURE 3 is a diagrammatic showing of control apparatus embodying theinvention, and adapted for association with the air conditionerillustrated in the preceding figures; and

FIGURES 4 and 5 are somewhat more detailed fragmentary showings of aportion of the control apparatus illustrated in FIGURE 3.

Description 0 the preferred embodiment With more detailed reference tothe drawing, there is seen in FIGURES l and 2 a window-mounted room airconditioner 10 including a cabinet '11 generally rectangular inconfiguration, and having a base portion 12 and a conventionaldecorative panel 13. The decorative panel comprises inlet and outletroom air passages for the air moving means to be more fully described.The inlet air passage includes grilles 1-4 and 18 disposed in the righthand region of panel 13, and in air flow communication with the inletopening 17 of the indoor blower 16 of the air moving means. A filter 15is positioned as shown, and is traversed by air flowing through grilles14 and 18. The outlet passage includes a grille 21 disposed in air flowcommunication with an evaporator coil 22. A plurality of independentlyrotatable louvers 23 are disposed between evaporator coil 22 and theinside surface of outlet grille 21, and are operable to provide forselection of the direction of outlet air flow.

Evaporator coil 22, preferably of the finned type, is part of the usualrefrigerating system including a motor compressor 24, a condenser 25,and associated conduits through which the motor compressor, thecondenser coil, and the evaporator coil are coupled in seriesrefrigerant flow circuit. These conduits (not shown) include a dischargeline through which refrigerant normally is delivered from the compressorto the outdoor coil or the condenser, and a feed line comprising acontinuously open restrictive connection through which liquifiedrefrigerant is normally fed to the indoor coil for expansion therein.Refrigerant is withdrawn by the compressor from the evaporator through asuction line to complete the refrigerant flow circuit. Compressor 24 isselectively energized by electrical circuit means hereinafter to be morefully described and including control panel 20.

Referring again to the air rnoving means, a motor 26 of the variablespeed type rotatably supports a blower wheel 27 operable to circulateair in heat exchange relation with evaporator coil 22. Blower wheel 27is housed within a scroll structure 31 disposed adjacent a partition 32which divides the cabinet into an evaporator coil chamber and acondenser coil chamber. The portion of cabinet 11 comprising one chamberis adapted to extend into a room or space to be air conditioned whileanother chamber, lying to the other side of partition 32, extendsoutwardly of the room, preferably through a window opening thereof. Theevaporator coil chamber is subdivided by another partition 33 into asection having disposed therein the blower wheel 27 and scroll 31, and asection in which there is disposed the evaporator coil 22, The mouthportion of scroll 31 extends through partition 33 and into cooperabledisposition with a sloping batlle 35 to direct air upwardly and againstone face of the evaporator coil which is positioned at an angle.

The condensing coil chamber also has disposed therein motor compressor24 and fan motor 26. A propeller-type fan 34 is rotatably supportedwithin the chamber by motor 26 to provide for drawing outside air intothe chamher over the coil 25 and for discharging the spent air outwardlyfrom the chamber over motor compressor 24.

Disposal means for condensate dripping from evaporator coil 22 includessloping baflle 35 disposed below the evaporator coil, and a trough 36extending across the batfie and feeding into a conduit 37 extendingthrough partition 32 and above a lower sump portion of base 12.Preferably fan 34 carries a conventional slinger ring (not shown), whichis adapted to dip into condensate collected in the sump portion of base12. As the fan rotates, condensate entrained by the ring is centrifugedonto a baffle plate 41 arranged to direct such condensate for flow overcondenser coil 25, for subsequent evaporation therefrom.

With reference also to FIGURE 3, control circuit means for achievingcapacity modulation according to the invention is arranged as shownrelative to a source of A.C. energy L L The circuit for energizing motorcompressor 24 includes a bellows-actuated thermostatic switch 42disposed in series electrical circuit with L L and motor compressor 24.A sensing bulb 43 for switch 42 is positioned in the path of air causedto flow into inlet 17 of blower scroll 31. Thermostatic switch 42 is ofthe adjustable type and may be set to achieve cyclic operation of themotor compressor.

Also in parallel electrical circuit with the compressor, and in serieswith L L is fan motor 26 and its associated control circuit formodulating the speed of the fan motor, whereby to vary the coolingcapacity of the air conditioner. Thermostatic switch 42 includeselements of the aforementioned associated control circuit. Consid eredin its entirety, and with reference also to both FIG- URES 4 and 5,switch 42 includes a single-pole singlethrow switch element 44 that isactuated through a levertype linkage 45 (FIGURE 3) by avapor-pressure-type bellows 46. Selectivity of temperature operatingrange is provided through a rotatable cam 47 coupled with a cam arm orfollower 51 arranged to vary the force on a spring (not shown) that isoperable, in turn, to vary the load on the bellows 46. Cam 47 isrotatable by a manual knob 52 to the desired temperature setting.

The structure of the thermostatic switch 42 as thus far described isconventional. The present invention involves provision of meansincluding a lever 53 actuatable by the switch linkage 45 when thetemperature sensed by control bulb 43 is above the compressor cut-outsetting. Lever 53 includes a set-screw S that abuts arm 59 of a vane 54pivotally mounted at 60 and interposed between a lamp 55 and a photocell56, such as, for example, a photoelectric device known as aphotoresistor. A tension spring 62 extends between the body of control42 and the vane 54 and maintains engagement of lever 59 against screw S.A shield 67 overlies the lamp 55 and is provided with a slotted aperture61 that predetermines the maximum intensity of light impinging onphotocell 56.

The lamp and photocell are wired into the circuit which is illustratedin FIGURE 3 and includes the variable speed fan motor 26. The circuit isso arranged that when vane 54 completely blocks off the light normallyimpinging upon photocell 56, fan motor 26 runs at high speed, and whenvane 54 permits full passage of light to the photocell, fan motor 26runs at low speed. Fan motor 26 is of the permanent capacitor,split-phase type, and is capable of having its speed infinitely variedbetween about 1100 and 550 rpm. Fan motor speed is varied between theselimits in correspondence to the quantity of light permitted by vane 54to impinge on photocell 56.

Speed control of fan motor 26 is achieved by means of a semiconductivedevice 38 known in the trade as a TRIAC and disposed in series circuitwith L L and the main winding 29 of motor 26. A capacitor 28 isconnected in series circuit with motor start winding 30, and elements28, and 30 are connected in parallel electrical circuit with the mainwinding 29 of the motor and its control circuit. Firing of the TRIAC 38is achieved by another semiconductive device 39 known in the trade as aDIAC and connected as shown in a circuit including the TRIAC 38, a pairof capacitors 40 and 48, and a resistor 49, each in series with oneanother while forming a circuit in parallel with motor 36 and the TRIAC.Photocell 56 is connected in parallel with capacitor 48, and functionsto control the rate of attainment of firing voltage applied by DIAC 39to TRIAC 38, and consequently the effective operating current applied tothe motor winding 29.

The photoresistor or photocell 56 is connected in series electriccircuit with L L capacitor 40, and resistor 49. The firing voltage forlow fan speed is preset by adjusting variable resistor 49. Fan speedsbetween low and high are controlled by variations in resistance of thephotoresistor, as provided by variations in the position of vane 54. Toensure uniform intensity of light emitted by lamp 55, it is connecteddirectly to L on the one hand, and to L on the other hand, throughresistors 50 and 58, and circuitry associated therewith as shown.

A series circuit comprised of a resistor 62 and capacitor 63 isconnected in parallel with TRIAC 38 to provide for suppression of thevoltage surge which is characteristic of an inductive load such as motor26. Finally, a capacitor 64 is connected in parallel circuit withcapacitors 40 and 48 and resistor 49 to provide radio frequencysuppression.

In operation of the hereinabove described apparatus, line switch 63 isclosed by operating a pushbutton on panel 20, and thermostat 42 is setfor a desired temperature range by positioning knob 52. This willinitially energize motor compressor 24 and fan motor 26, the latter atits full, or high speed. The fan motor will be operating at full speedbecause vane 54 will be in such position as to block light radiated bylamp 55 from impinging on photocell 56. Under this condition, TRIAC 38operates to deliver full power to fan motor 26. As the temperature ofthe room is reduced, and bellows 46 has contracted to approach suchposition as to open switch 44, vane 54 begins to be moved, by linkage53, to a position uncovering a portion of aperture 61. Light begins toimpinge on photocell 56, thereby generating a gate signal in DIAC 39,causing TRIAC 38 to deliver reduced power to the fan motor and therebyreducing its speed. As the vane continues to move, power delivered tothe motor, and hence its speed, will be decreased at a rate proportionalto the quantity of light impinging on the photocell, or photoresistor,By the time switch 44 has opened, aperture 61 is fully uncovered by thevane 50 to permit full impingement of light on the photocell, withconsequent low speed operation of the fan motor and deenergization ofmotor compressor 24.

Vane 54 .and its associated linkage 53 is so constructed and arranged asto remain in this position until such time as the cut-in temperature ofthermostat 42 is attained to close switch 44 and again energize themotor compressor. Closure of switch 44 results in movement of linkage 53to cause vane 54 again to begin to cover aperture 61. Subsequentmovement of the vane to effect increased covering of the aperturereduces impingement of light on the photocell, thereby permittingdelivery of increased power to the fan motor, with consequent operationat higher speed to increase the cooling capacity.

While a preferred electrical circuit has been shown for deriving a fanmotor speed change signal from photoresistor 56, it will, of course, beunderstood that other known circuit arrangements may be used inachieving the inventive combination set forth in the appended claims andbriefly described in the earlier-presented summary of the invention.

I claim:

1. In air conditioning apparatus, cooling means, means operable toenergize said cooling means, a fan for moving air over said coolingmeans, a variable speed motor for operating said fan, and manuallyadjustable control means for regulating energization of said coolingmeans in response to temperatures of air being caused to move over thecooling means, said control means further being operable to decrease thespeed of said fan motor at a rate corresponding to the rate of reductionof air temperature sensed by said control means, said control meanscomprising: a temperature sensing element and linkage means driventhereby and movable between predetermined limits in correspondence tosensed temperatures; switch limits in correspondence to sensedtemperatures; switch means operable by said linkage means to energizesaid cooling means at a higher air temperature value and to deenergizesaid cooling means at a lower air temperature value; and means operableby said linkage means continuously to vary the speed of said fan motorin a range comprising maximum speed upon energization of said coolingmeans and minimum speed upon deenergization of said cooling means, saidlast recited means comprising a photoelectric device and circuit meansassociated therewith operable to modulate the fan motor speed, a lampfor directing light onto said photoelectric device, a movable vaneinterposed between said lamp and said photoelectric device, and meansoperably coupling said vane to said movable linkage means to vary thequantity of light impinging on said photoelectric device, andconsequently to vary the speed of the fan motor.

2. In air conditioning apparatus, cooling means comprising a refrigerantevaporator means operable to energize said cooling means comprising arefrigerant motor compressor, a fan for moving air over said coolingmeans, a variable speed motor for operating said fan, and manuallyadjustable control means for regulating energization of said coolingmeans in response to temperatures of air being caused to move over thecooling means, said control means further being operable to decrease thespeed of said fan motor at a rate corresponding to the rate of reductionof air temperature sensed by said control means, said control meanscomprising: temperature sensing means and linkage means movable therebybetween predetermined limits in correspondence to temperatures sensedthereby; switch means operable by said linkage means to energize saidmotor compressor at a higher air temperature and to deenergize saidmotor compressor at a lower air temperature; and means operable by saidlinkage means continuously to vary the speed of said fan motor within arange comprising maximum speed upon motor compressor energization andminimum speed upon deenergization, said last recited means comprising aphotoresistor and circuit controlled thereby operable to modulate thefan motor speed, means for directing light onto said photoresistor,movable vane means for varying the intensity of light impinging on saidphotoresistor, and meas operably coupling said vane to said movablelinkage means to vary the quantity of light impinging on saidphotoresistor, and consequently to modulate the speed of the fan motor,in accordance with the sensed air temperature.

3. For use in an air conditioner having a refrigeration systemcomprising a motor compressor, a condenser, an evaporator, fan means fordirecting individual air streams over said condenser and evaporator, anda variable speed motor for said fan means, control means comprising: atemperature sensing element movable between predetermined limits incorrespondence to temperatures of the evaporator air stream sensedthereby; switch means operable in correspondence with temperaturesdetected by said sensing element to energize said motor compressor at ahigher evaporator air stream temperature and to deenergize said motorcompressor at a lower air stream temperature; and fan speed modulatingmeans operable in correspondence with temperatures detected by saidsensing element to vary the speed of such fan motor throughout a rangeincluding higher speeds while the motor compressor is energized and aminimum speed upon motor compressor deenergization, said last recitedmeans comprising a photoelectric device and a circuit controlled therebyand operable to modulate fan motor speed, a lamp for directing lightonto said photoelectric device, a movable vane for varying the intensityof light impinging on said photoelectric device, and means operablylinking said vane to said movable sensing element to vary the quantityof light impinging on said photoelectric device, and consequentlymodulate the speed of such fan motor, in accordance with the sensedtemperaturc.

4. In air conditioning apparatus, cooling means, means operable toenergize said cooling means, means operable to direct air over saidcooling means, and means for varying the cooling effect of said coolingmeans comprising manually adjustable control means for regulatingenergization of said cooling means in response to temperatures of airmoving over the latter, said control means further being operablecontinuously to modulate the air directing means to effect a decrease inair flow as the air temperature is decreased, said control meansincluding: a temperature sensing element movable between predeterminedlimits in correspondence to temperatures sensed thereby; switch meansoperable by said sensing element to energize said cooling means at ahigher air temperature and to energize said cooling means at a lower airtemperature; and means operable by said sensing means to modulate theair directing means while the cooling means is energized in a rangecomprising higher air fiow at higher temperatures and lower air flow atlower air temperatures, said last recited means comprising aphotoelectric device operable to modulate the air directing means, alamp for directing light onto said photoelectric device, a movable vaneinterposed between said lamp and said photoelectric device, and meansoperably linking said vane to said movable temperature sensing elementto vary the quantity of light impinging on said photoelectric device andconsequently the rate of air flow over the cooling means.

5. In air conditioning apparatus, cooling means, means operable todirect air over said cooling means, and control means operable tomodulate the air directing means, said control means including: atemperature sensing element movable between predetermined limits incorrespondence to temperatures sensed thereby; and means operable bysaid sensing means to modulate the air directing means, and achievehigher air flow at higher air temperatures, said last recited meanscomprising a photoelectric device operable to modulate the air directingmeans in accordance with the quantity of light impinging thereon, meansfor directing light onto said photoelectric device, and means operableby said movable temperature sensing element to vary the quantity oflight from said source impinging on said photoelectric device, andconsequently to vary the rate of air flow over the cooling means.

References Cited UNITED STATES PATENTS 2,236,058 3/1941 Henney 62-1802,770,101 11/1956 Smith 62180 3,009,332 11/ 1961 Spiegelhalter 62-1803,034,314 5/1962 Canter 62-180 3,070,972 1/ 1963 Atchison 621803,276,220 10/1966 Miner 62180 3,324,672 6/1967 Sones 62-180 WILLIAM J.WYE, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Column 1,after-line 22,-, insert Column' 5", line 15, cancel "switch limitsBackground of temperatures,-"; line 58, "meas" the Invention incorrespondence to sensed shouldread'- means Signed andsealenthis 3rd dayof March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, Attesting OfficerCommissioner of Patents

